diskimage-builder/diskimage_builder/block_device/utils.py
Ian Wienand 35a1e7bee9 Refactor mount-point sorting
Currently we keep a global list of mount-points defined in the
configuration and automatically setup dependencies between mount nodes
based on their global "mount order" (i.e. higher directories mount
first).

The current method for achieving this is roughly to add the mount
points to a dictionary indexed my mount-point, then at "get_edge()"
call build the sorted list ... unless it has already been built
because this gets called for every node.

It seems much simpler to simply keep a sorted list of the
MountPointNode objects as we add them.  We don't need to implement a
sorting algorithm then, we can just use sort() and implement __lt__
for the nodes.

I believe the existing mount-order unit testing is sufficient; I'm
struggling to find a valid configuration where the mount-order is
*not* correctly specified in the configuration graph.

Change-Id: Idc05cdf42d95e230b9906773aa2b4a3b0f075598
2017-05-31 11:05:50 +10:00

126 lines
3.8 KiB
Python

# Copyright 2016 Andreas Florath (andreas@florath.net)
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import logging
import re
import subprocess
logger = logging.getLogger(__name__)
SIZE_UNIT_SPECS = [
["TiB", 1024**4],
["GiB", 1024**3],
["MiB", 1024**2],
["KiB", 1024**1],
["TB", 1000**4],
["GB", 1000**3],
["MB", 1000**2],
["KB", 1000**1],
["T", 1000**4],
["G", 1000**3],
["M", 1000**2],
["K", 1000**1],
["B", 1],
["", 1], # No unit -> size is given in bytes
]
# Basic RE to check and split floats (without exponent)
# and a given unit specification (which must be non-numerical).
size_unit_spec_re = re.compile("^([\d\.]*) ?([a-zA-Z0-9_]*)$")
def _split_size_unit_spec(size_unit_spec):
"""Helper function to split unit specification into parts.
The first part is the numeric part - the second one is the unit.
"""
match = size_unit_spec_re.match(size_unit_spec)
if match is None:
raise RuntimeError("Invalid size unit spec [%s]" % size_unit_spec)
return match.group(1), match.group(2)
def _get_unit_factor(unit_str):
"""Helper function to get the unit factor.
The given unit_str needs to be a string of the
SIZE_UNIT_SPECS table.
If the unit is not found, a runtime error is raised.
"""
for spec_key, spec_value in SIZE_UNIT_SPECS:
if unit_str == spec_key:
return spec_value
raise RuntimeError("unit_str [%s] not known" % unit_str)
def parse_abs_size_spec(size_spec):
size_cnt_str, size_unit_str = _split_size_unit_spec(size_spec)
unit_factor = _get_unit_factor(size_unit_str)
return int(unit_factor * (
float(size_cnt_str) if len(size_cnt_str) > 0 else 1))
def parse_rel_size_spec(size_spec, abs_size):
"""Parses size specifications - can be relative like 50%
In addition to the absolute parsing also a relative
parsing is done. If the size specification ends in '%',
then the relative size of the given 'abs_size' is returned.
"""
if size_spec[-1] == '%':
percent = float(size_spec[:-1])
return True, int(abs_size * percent / 100.0)
return False, parse_abs_size_spec(size_spec)
def exec_sudo(cmd):
"""Run a command under sudo
Run command under sudo, with debug trace of output. This is like
subprocess.check_call() but sudo wrapped and with output tracing
at debug levels.
Arguments:
:param cmd: str command list; for Popen()
:return: nothing
:raises: subprocess.CalledProcessError if return code != 0
"""
assert isinstance(cmd, list)
sudo_cmd = ["sudo"]
sudo_cmd.extend(cmd)
try:
logger.info("Calling [%s]", " ".join(sudo_cmd))
except TypeError:
# Popen actually doesn't care, but we've managed to get mixed
# str and bytes in argument lists which causes errors logging
# commands. Give a clue as to what's going on.
logger.exception("Ensure all arguments are str type!")
raise
proc = subprocess.Popen(sudo_cmd,
stdout=subprocess.PIPE,
stderr=subprocess.STDOUT)
for line in iter(proc.stdout.readline, b""):
logger.debug("exec_sudo: %s", line.rstrip())
proc.wait()
if proc.returncode != 0:
raise subprocess.CalledProcessError(proc.returncode,
' '.join(sudo_cmd))